US2425234A - Automatic grinding machine - Google Patents

Description

R. ERWIN 1- -r AL AUTOMATIC GRINDING MACHINE Filed July so, 1945 4 Sheets-Shet 1 INVBNTORS R0) ER WIN fDW/IV TROUTMAN L504! W. LINDQUIST ATTORNEY 1947- R. ERWIN ETAL I AUTOMATIC GRINDING MACHINE 4 Sheets-Sheet 2 Filed July 30, 1945 \llllllllll RoY ERWIN [DWI/v TROUT/MN BY LEON W. LINDQU/ST Aug. 1947- Y R. ERWlN ETAL I 2,425,234

AUTOMATIOGRINDING MACHINE Filed July 30, 1945 4 Sheets-Sheet 4 mvsN'rbRs Rov ERwnv' 6 Eawnv TROUT/VAN v LEON w. L/NDQ u/sT BY ATTORNEY Patented Aug. 5, 1947 AUTOMATIC GRINDING MACHINE Roy Erwin, University Heights, Edwin Troutman, Bedford, and Leon W. Lindquist, Lyndhurst, Ohio, assignors to National Malleable and Steel Castings Company, Cleveland, Ohio, at corporation of Ohio Application July 30, 1945, Serial No. 607,770

6 Claims.

The invention relates to grinding machines.

An object of our invention is to provide improved power-actuated means for manipulating work against a grinding wheel without intervention of an operator during a complete operating cycle, or a number of operating cycles, during which different portions of the work can be brought against the wheel in succession or the work can be swung back and forth across the wheel while held against it, or during which other manipulations or various combinations of these manipulations can be performed according to a predetermined cycle or cycles.

Another object is to provide a work holder for grinding machines which will automatically clamp the work in position on the holder by the operation of the machine.

Other objects and advantages of our invention will appear as the description proceeds.

In the drawings,

Fig. 1 is a side elevational vie-w, partly in section, illustrating the application of our invention to a machine particularly adapted to grinding off the gate of a small casting.

Fig. 2 is a front elevational view of the machine shown in Fig. 1; and Fig. 3 is a top plan view of the same machine. (In Fig. 3, part of the Work clamping mechanism has been removed to show other parts more clearly.)

Fig. 4 is a circuit diagram of a preferred form of automatic electrical means for controlling the cycles of operation of the work holder of the machine shown in Figs. 1 to 3, inclusive.

Figs. 5, 6, 7 and 8 are diagrammatic views illustrating successive positions of the work holder in relation to the grinding wheel during operation of the machine.

Referring more particularly to Figs. 1, 2 and 3, the machine comprises, in its general arrangement, a grinding wheel 9 with suitable mounting and driving means therefor, a work holder or supporting table Hi mounted for pivotal movement selectively about a horizontal axis A-A (Fig. 2) and a vertical axis BB (Fig. 1), fluid operated means for imparting pivotal movement to the work holder about the two axes, which means comprise an air cylinder mechanism l l for tilting the work holder about'axis A-A to move the work toward and away from the grinding wheel 9,. and an air cylinder mechanism I2 for oscillating the work holder about axis BB to move the work across the face of the grinding wheel, and the automatic electric control means, shown diagrammatically in Fig. 4, for directi g iii a complete cycle of operation of the fluid operated means.

Our power-actuated means for manipulating the work, which comprises the aforesaid fluid operated devices and automatic controls therefor, is applicable to hand grinding machines of conventional construction such as that shown in Figs. 1 to 3 by way of illustration, and which comprises a main supporting frame l3 on which the grinding wheel 9 is mounted and powerdriven from any suitable source such as an electric motor (not shown). The supporting frame for the fluid operated mechanism and workholder may be mounted on the main supporting frame l3 of the grinder, and in our preferred construction we have provided an adjustable mounting which comprises an inner guide member I4 which may be bolted to the front of the frame l3 as at I5 (Fig. 3) and an outer guide member [6 which has a telescoping engagement with the inner guide l4. Adjustment of the outer guide member 86 is effected by a hand wheel ll fixed to a shaft l8 passing through an aperture H9 in the front of the outer guide member l6 and threaded as at 20 for engagement with a threaded aperture in the sleeve 2| fixed to the inner guide member I4. Longitudinal movement of the shaft l8 relative to the outer guide member I6 is preventedby engagement of the hub of the hand wheel ll with the outer face of the guide member, and engagement of a collar 22 fixed to the shaft with the inner face of the guide member. Turning of the hand wheel I! moves the outer guide member It to the right or left as viewed in Fig. 1, as may be desired in accordance with the size of the casting or other work W which is to be handled. A locking screw 23, threaded in the outer guide member [5, bears against the inner guide member 14 when tightened, retaining the outer guide member in its adjusted position.

The two guide members may be of welded or cast construction, the latter being indicated in the drawings by way of illustration, the members being of box-like formation and the outer guide member l6 fitting over the inner guide member M to provide the telescoping arrangement previously referred to. The two guide members may be widened out at the top as shown at 24 (Fig. 2), the widened portions being joined to the main part by inclined walls as at 25. If desired, a clearance may be provided between the side walls of the guide members as at 26, smooth sliding engagement between the members being provided by means of a series of wear plates 21, 28 fixed respectively to the inner and outer members l4 and I6. When made as castings, these plates can be formed integrally, and the engaging surfaces can be machined.

The air cylinder mechanism ll, l2 or other fluid operated means are mounted on the outer guide member IS in any convenient manner. For this purpose, in the construction shown, laterally extending vertical and horizontal flanges 26, 36 joined to a side wall of member l6 form a support for a sleeve 3| in which is journaled a shaft 32 to support the work table 16. To the lower end of shaft 32 is fixed a bracket 33 having a projecting arm 34 suitably reinforced by a flange 35 which connects it to the sleeve portion of the bracket. The form of the projecting arm 34 of the bracket is best shown in Fig. 3. It has a series of apertures 36 arcuately disposed about the center of pivot 46 when the work table I!) is in its center position to provide an adjustable engagement with the clevis of a piston rod 3'! associated with the air cylinder 33 of the fluid operated mechanism 12 for oscillating the work holder about the axis B-B.

The end of the cylinder 38 is provided with a lug, or lugs, 39 pivotally connected as by a pin 46 to a bracket 4| secured to the under side of the outer guide member l6, as by the bolts 42, or otherwise fixed to the guide member. The extent of the arc of oscillation of the work holder about vertical axis BB is adjusted by selection of the point of pivotal attachment 64 of the clevis 65 of the piston rod 31 of the fluid operated mechanism [2. Thus, if a somewhat smaller arc of oscillation i desired for the grinding operation to be performed on a particular casting, the attaching pin of clevis 65 is removed and the clevis is attached to one of the apertures which is farther removed from the oscillation axis B-B.

Bracket 34 is provided with an upstanding lug 43 for pivotal attachment to a lug, or lugs, 44 fixed to the lower end of air cylinder 45 of the fluid operated mechanism ll. Piston rod 46 of the air cylinder 45 terminates in a clevis 41 for pivotal attachment to a lever 48 as by the pin 43 for operation of the automatic work clamping mechanism and to produce pivotal movement of the work supporting table [6 about the horizontal axis AA.

The work holder or supporting table In may be of any form suitable for holding the articles to be processed. This work holder is pivotally attached to the upper end of shaft 32 as by means of pin 50 passing through the shaft, or through a block attached to the top of the shaft, and through a depending lug, or pair of lugs, fixed to the work holder. A stop lug 52 fixed to the end of the shaft 32, or to the block attached thereto, engages the under side of the work holder to the right of the pivot 50 as viewed in Fig. 1, to limit the extent of pivotal movement of the work holder in the direction which brings the work against the grinding wheel 9.

The lever .48 of the operating mechanism is pivotally attached as by a pin 53 to a lug or pair of lugs 64 on the under side of the work table. Another pair of lugs 56 on the top of the work holder provide for pivotal attachment of a work clamping lever 56 as at 56'. The clamping lever is attached to the operating lever 48 by a pair of links 51 pivotally attached to the clamping lever at 58 and to the operating lever at 59. The links 51 pass through apertures 60 in the work holder. At the inner end of t WQ K.

clamping lever 56 is a bolt 6| and lock nut 62, providing an adjustable clamp for the work W. Supplemental work holding means of any suitable form, such as the stop 63, may be provided, depending upon the form and ize of the work to be handled.

It will be understood that upon retraction of the piston 46 into the cylinder, the work holder [6 is caused to pivot about the axis AA at the pivot 56 attached to shaft 32, moving in a counterclockwise direction as viewed in Fig. 1, and thus retracting the work from the grinding wheel. At the same time, downward movement of the operating lever 48 causes the clamping lever 56 to pivot about its attachment at 56', lifting the bolt 6|, releasing the work for removal, and permitting its replacement by the next casting which is to be processed. Adjustment of the movement of the clamping lever is afforded by the selection of pivotal attachment points 49, 49 for the clevis of the piston rod.

Through selective actuation of the fluid operated mechanisms H and I2, different portions of the work W can be brought against the grinding wheel in succession or the work can be swun back and forth across the wheel while held against it, or other manipulations or various combinations of these manipulations can be performed. Selective operation of the fluid operated mechanisms in accordance with a cycle or series of cycles of predetermined pattern is obtained without intervention of an operator by means of an automatic electric control which we shall now describe with reference to the diagram, Fig. 4. A rotary contact drum 66 (which, for convenience of illustration, has been shown in developed form so that the entire 360 of its circumference appears in the plane of the diagram) controls the operation of valves 61, 68 which operate the air cylinders II and 12, respectively. Valve 61 is connected to the cylinder l l for pivoting the work holder about the horizontal axis A-A to move the work toward and away from the grinding wheel 9. Valve 68 is connected to the cylinder [2 for oscillating the work holder about vertical axis BB to move the work across the face of the grinding wheel. The connections of the valves to the cylinders are not shown, but are indicated diagrammatically by correspondence of the letters C, D, E, and F on the diagram, Fig. l, and in Figs. 1-3; The line G leads to both valves from a suitable source of compressed air.

Valves 61 and 6B are electrically operated. Conventional means may be used for this purpose, and it is to be understood that such means are incorporated in the valves which we have shown diagrammatically. Actuation of the electrically operated valves is initiated through relays 69, 1!) from a suitable power source such as the line H. One side of this line is directly connected in parallel to the two relays, as shown. The other side of the line is connected to the relays through the control drum 66. The shaft of this drum is indicated at 12, and it is driven by a motor 13 connected to the line H through a relay (4. In series with the relay 14 is a starting switch 75. One side of the starting switch connects to the line. The other side of the starting switch connects directly to the relay and through it to the other side of the line; and also connects to the first side of the line through the contacts on the operating drum and the relay 14.

The drum is shown in neutral position in which the brush 16 at the left of the drum is touching the circumferential contact strip 1'|. When the starting switch is closed, a circuit is completed through the solenoid of the relay [4, switching-in the motor 13 to actuate the drum 66. (Motor 13 may be direct-connected to the drum, or may actuate the drum through suitable reducing gears or .the like.) The circumference of the drum travels in the direction indicated by the arrow 18. After the drum has rotated slightly, the starting switch 15 can be released, because the circuit through the solenoid of the motor relay I4 is sustained through relay 14, line 19, brush 16, contact 11, and one of the other contact strips on the drum in accordance with the selective control to be described.

The drum 66 is designed to afford selective control of the operation of the machine in accordance with any one of a number of predetermined cycles or combinations of cycles after which the operating drum will automatically come to rest, retracting the work holder and clamping means for removal of the completed work and insertion of the new work. Thus in the preferred embodiment illustrated, we have provided a series of three sets of control contacts H, J, K, each comprising three control bands, one for the motor circuit and one each for the operating relays of the control valves 61 and 68 of the fluid operated means. For convenience of reference, the lefthand band of each set will be referred to as the motor band, the center band as the oscillation band and the righthand band as the pivoting band. It will be understood that both the center and righthand bands control movements which may be described as either pivoting or oscillation. However, for purposes of ready distinction, the term oscillation as used in the description is reserved for the band which controls movement about axis BB, and the term pivoting is reserved for the band which controls movement about the axis AA. This is done as a matter of convenience only and is not intended to be a limiting definition of these terms as employed in the claims. Selection of the desired group of control bands is obtained by means of a threeway switch 80. This switch is shown in its righthand position where it selects the group of contact bands K. (When this switch is in its mid-position contact group J is effective, and when in its lefthand position contact group H is effective.) In each group the lefthand contact band controls the operation of the motor. The center band controls the operation of valve 68, air cylinder I2, and oscillation about axis BB. The righthand band controls the operation of valve 61, air cylinder l l, and pivotal movement about axis A-A. The segments of each band are interconnected as at 8|, and all bands are connected to the main control band T! as shown at 92.

The three band groups H, J and K provide control means constructed and arranged to direct a plurality of different operating cycles. The three-way switch 89 provides means to predetermine the cycle of operation.

Referring specifically to the band group K for Which the three-way switch 80 is in its selective position, it will be observed that the motor contact band consists of a single band 83, the center or oscillation band comprises a series of segments 84, 85, 86, 81, and the righthand or pivoting control band comprises a series of segments 99, 9|, 92, 93.

Operation Consider that the control drum 66 is in its neutral, or starting, position shown in Fig. 4, that a casting W has been placed on the work holder in position for grinding off the gate, and that the grinding wheel 9 is operating. Upon depressing the starting switch 15, the circuit of the control drum motor i3 is closed through the relay M as previously described. After the control drum has been started, the switch 15 is released and operation of the motor 13 is sustained through the main band TI, and motor band 83, and will be so sustained until the drum has rotated for nearly 360, or for one complete cycle of operation.

As soon as the brush or contactor 94 makes contact with the leading end of the first segment of the pivoting band, relay B9 is actuated to operate the valve 51. Operation of this valve connects the air inlet to the lower end of cylinder I I at D and brings the outlet G into communication with the atmosphere for exhaust. This actuates the piston to raise the rod 46, and through it the lever 48, links 57!, and lever 56 to clamp the work. The instant that the work is clamped, further movement of piston rod 49 raises the work holder 10 toward the position shown in Fig. 1, bringing a corner of the work against the surface of the grinding wheel. Thus operation of air cylinder H to tilt the table In and move the work toward the grinding wheel also clamps the work to the table by transmitting to the pivotally mounted member 56 a component of the table-tilting force. As this action takes place, the work holder may be in the position indicated diagrammatically in Fig. 5, the piston of air cylinder 38 being over to the right from the center position shown in Fig. 3.

The work is pressed resiliently against the grinding wheel by the air cylinder 45 until the control drum has rotated to the point where brush 94 leaves band segment 99. At this point, the circuit through the solenoid of relay 69 is broken, reversing valve 61 to connect the upper end C of cylinder 45 with the air supply and place the lower end D of the cylinder in communication with the atmosphere. This retracts the piston and brings the work holder l0 into the position illustrated diagrammatically in Fig. 6, withdrawing the work from the grinding wheel.

A slight additional rotation of the drum brings brush 95 into contact with the first segment 84 of the oscillation band. This completes a circuit through relay 10 to actuate valve 68, admitting compressed air at F to the cylinder 38, oscillating the work holder about axis BB until it reaches the position illustrated diagrammatically in the upper part of Fig. 7. Additional rotation of the drum brings the brush 94 into contact with the leading end of the next segment 9| of the pivoting band, raising the work holder to the position shown in the lower part of Fig. 7, and bringing another part of the work against the grinding wheel 9 (compare Fig. 7 with Fig. 5). As brush 94 leaves the trailing end of segment 9| of the pivoting band, the work holder is again brought into the position indicated in Fig. 6 by operation of the valve 61 as described. Upon slight additional rotation of the drum, the brush 95 leaves the trailing end of segment 84 of the oscillation band, reversing the air connections of cylinder 38 and causing the work holder to oscillate about axis BB into the position shown in the upper part of Fig. 5.

As brush 94 contacts'the leading end of the next segment 92 of the pivoting band, the work holder again is brought into the raised position shown in the lower part of Fig. 5. As brush 94 leaves the trailing end of band segment 92, the work holder is brought into the position shown in Fig. 6, and thereafter as brush 95 makes contact with the leading end of segment 85 of the oscillation band, the work holder oscillates into the position shown in upper part of Fig. '7. Thereafter, as brush 94 makes contact with the leading end of pivoting band segment 93, the work holder is brought into the position shown in the lower part of Fig. '7, urging the work against the grinding wheel. As brush 95 leaves the trailing end of oscillation lband segment 85, the work holder oscillates again, but this time the oscillation 1S performed while the work is held against the wheel as distinguished from the condition described during the previous oscillations, when the work was withdrawn. Again, as brush 95 passes over oscillation band segments 86 and 81, the holder is caused to oscillate back and forth with the work in contact with the grinding wheel, this being the condition illustrated diagrammatically by the arrow 99 in Fig. 8. Thus the fluid operated means I I and I2, as controlled by the oscillation and pivoting bands, are arranged for both independent and conjoint operation whereby the work can be moved across the face of the grinding wheel while held selectively in contact and away from contact therewith.

Finally, at the end of the cycle controlled by band group K, brush 96 leaves the motor segment 83 breaking the motor circuit, and brushes 94 and 95 leave the final segments 93 and 81 of the pivoting and oscillationbands, respectively, concluding the cycle.

During the times that the work is urged against the wheel, whether during periods of oscillation or during periods when there is no oscillation about axis BB, the exact position of the work holder in respect of its pivoting movement about axis A-A is determined by the amount of grinding which has been performed. When the work holder reaches the fully horizontal position shown in- Fig. 1, the cycle will have been completed. Over-grinding is prevented by the stop 52 which engages the under side of the work holder, as has been described.

The operation as controlled by band groups H and J will be understood from the description which has preceded. With band group J there are two complete cycles of operation for each rev olution of the drum 65, and with band group H there are three complete cycles for each revolution of the drum. However, the two segments I09, IOI of the motor band of group J may be replaced by a single continuous band if it is desired to complete two cycles of operation without intervention of the operator. Similarly, the three motor control segments I92, I03- and I04 of band group H may be replaced by a single continuous band if it is desired that three complete cycles of operation be performed without intervention of the operator, or intervening use of the starting switch 15.

It will be understood that the length of the grinding intervals is determined by the length of the respective contact segments 90, 91, 92, etc., of the pivoting bands of the control drum, in conjunction with the peripheral speed thereof. A variable speed motor, or other speed control means, may be used in the drive for the drum. Adjustment can thus be made so that timing will be governed in accordance with the size of the gate or the amount of metal which is to be removed from the casting during each grinding interval and during the complete cycle.

The terms and expressions which we have employed are used in a descriptive and not a limiting sense, and we have no intention of excluding such equivalents of the invention described, or of portions thereof, as fall within the purview of the claims.

We claim:

1. A grinding machine comprising a work holder, a grinding wheel, fluid operated means for tilting the work holder to move the work toward and away from the grinding wheel, and fluid operated means for oscillating the work holder to move the work across the face of the grinding wheel, the last-named fluid operated means being arranged for operation independently of the first-named means.

2. A grinding machine comprising a work holder, a grinding wheel, fluid operated means for moving the work holder toward and away from the grinding wheel, and fluid operated means for oscillating the work holder to move the work across the face of the grinding wheel, the last-named fluid operated means being arranged for operation independently of and conjointly with the first-named means whereby the work can be moved across the face of the wheel while held selectively in contact and away from contact therewith.

3. A grinding machine comprising a work holder, a grinding wheel, fluid operated means for moving the work holder toward and away from the grinding wheel, fluid operated means for oscillating the work holder to move the work across the face of the grinding wheel, the lastnamed fluid operated means being arranged for operation independently of and conjointly with the first-named means whereby the work can be moved across the face of the wheel while held selectively in contact and away from contact therewith, and automatic electric control means for controlling a complete cycle of operation of the two fluid operated means.

4. A grinding machine comprising a work holder, a grinding wheel, fluid operated means for imparting pivotal movement to the work holder selectively about two axes, automatic electric control means for controlling the cycle of selective operation of the fluid operated means, said control means being constructed and arranged to direct a plurality of difierent operating cycles, and means for setting the control means to predetermine the cycle of operation.

5. A grinding machine comprising a table, a grinding wheel, means on the table for positioning and clamping work thereon, and an air cylinder mechanism for tilting the table to move the work toward and away from the grinding wheel, the means for clamping the work on the table comprising a member pivotally mounted on the table and a link connecting said member to the air cylinder mechanism, whereby operation of the air cylinder to tilt the table and move the work toward the grinding wheel clamps the work to the table by transmitting to said pivotally mounted member a component of the tabletilting force.

6. A grinding machine comprising a work holder, a grinding tool, fluid operated means for imparting pivotal movement to the work holder selectively about two axes, and automatic electric control means including a control drum hav- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,871,494 Carlson Aug. 16, 1932 2,202,587 Kitchen May 28, 1940 10 2,040,449 Stevens May 12, 1936

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